Diagnostic assays are biochemical techniques that may be used to detect and identify pathogens (e.g., harmful bacteria, viruses, organism, etc.) and/or diseased cells. One known diagnostic assay involves the use of polymerase chain reaction (PCR), which uses a DNA polymerase to amplify a piece of DNA, i.e., a target DNA, by in vitro enzymatic replication. PCR is capable of rapidly amplifying a DNA sequence initially present in minute concentrations, ultimately producing millions of identical DNA molecules and, thus, exponentially increasing the detection sensitivity toward the respective DNA sequence/target.
Some diagnostic assays also include selectively capturing detection targets such as amplified DNA sequences, biomarker molecules, pathogens and/or other targets, removing the targets from a large sample and docking the targets to a molecular probe. The docked targets can be detected with various techniques including optical sensor technologies that are based on fluorescent tagging or emission, Raman, and IR or UV spectroscopy.
These diagnostic assays are routinely used in genetic diagnostic techniques in medical diagnostic laboratories. In addition, grocery stores, food growers, processors, distributors and/or manufacturers use diagnostic assays such as enzyme-linked immunosorbent assays to detect bacteria such as E. Coli in fresh produce. While these techniques are useful for bacteria detection or the detection of other DNA, biomarkers or other targets, they are typically encumbered by expensive, slow, and heavy laboratory equipment, often require extensive manual supervision and handling, and take days or longer to produce results (e.g., TB bacteria require a week to culture).
Portable PCR kits are also commercially available; however, these assays have at least an hour-long response time, which is typically too long for portable field-use devices or for high-throughput biomarker screening. In addition, the conventional assays kits still perform single-target detection using a batch format with low-throughput, which has a low target count and questionable sensitivity.